TruTrak Yaw Damper User Manual

Yaw Damper System

Installation Manual

83000-63 Rev C

TRUTRAK FLIGHT SYSTEMS

1500 S. Old Missouri Road

Springdale, AR 72764

Ph: 479-751-0250 Fax: [phone]

www.trutrakap.com

INSTALLATION MANUAL

For

Yaw Damper Systems

TABLE OF CONTENTS

Mechanical Installation Considerations.................................................................................1

RFI/EMI considerations.........................................................................................................1

Basic Servo Installation..........................................................................................................2

Yaw Damper Initial Setup & Checkout.................................................................................3

First Flight Yaw Damper .......................................................................................................4

Electrical Pin-Out...................................................................................................................5

Sorcerer Installation ...............................................................................................................6

DII installation........................................................................................................................7

Trouble Shooting....................................................................................................................8

Revision Date Description Page #

A 07/01/2008 Initial Release

B 06/18/2009 New mod wiring change 3, 5,6,7
C 12/07/2009 Updated Warranty information 8

Mechanical Installation Considerations

MODULE INSTALLATION

Mounting Considerations
The Yaw Damper module is designed to mount on a vertical bulkhead or horizontal surface in the

aircraft, with the bottom flange level with the aircraft, as shown on the first page. Level to the
aircraft, installation is very important as the knob on the YD module will only remove a slight
discrepancy in leveling. Install the wire connector pointing forward or aft, see installation initial
check out for details. Use aircraft installation standards for mounting and support of the YD
system.

Wiring Considerations
Use AWG #24 or larger wire for all connections unless otherwise specified. The standard solder

pin contacts supplied in the connector kit are compatible with up to AWG #18 wire. In cases
where some installations have more than one component sharing a common circuit breaker, sizing
and wire gauge is based on, length of wiring and current draw on units. In these cases, a larger
gauge wire such as AWG #20 may be needed for power connections. Do not attach any wires to
the outside of the YD or route high current wires within six (6) inch of the module. Ensure that
routing of the wiring is not exposed to sources of heat, RF or EMI interference. Check that there
is ample space for the cabling and mating connectors. Avoid sharp bends in cabling and routing
near aircraft control cables.

RFI/EMI considerations

The YD module is shielded and does not generate any appreciable level of electromagnetic
interference. Moreover, the servo lines (except for power and ground) are low-current and cannot
contribute to RF interference. The servo power and ground lines do have switching currents
through them, but so long as there are no parallel runs of servo power and ground lines with such
things as poorly-shielded antenna lines or strobe light power lines, there is no need to shield the
servo harnesses. The YD module itself has been internally protected from RF interference and
has been tested under fairly extreme conditions, such as close proximity to transmitting antennas.
However, it is always good practice to insure that such antennas are properly shielded and not
routed directly over or under sensitive panel-mounted electronic equipment. Most problems in
this area are the result of improper RF shielding on transmitting antennas, microphone cables, and
the like.

TruTrak Flight Systems Yaw Damper Installation Manual
December 2009 1 8300-063 Rev C

Servo Installation

The installation information in this section is extremely important and must be
clearly understood by the installer. Improper servo installation or failure to observe
and diagnose installation problems prior to flight can result in extremely serious
consequences, including loss of ability to control the aircraft. If there are any
questions on the part of the installer it is mandatory to resolve these questions prior

to flight of the aircraft.

Most modern experimental aircraft use push-pull tubes to drive the primary controls. These tubes
generally have a total travel of 3” or less; therefore, it is best to connect the autopilot servo to the
primary control by the same method. This connection consists of an arm on the servo connected
by a push-pull rod to the primary control. Rod-end bearings are required on each end of the push­pull rod. The servo arm must not rotate even near to the point called OVER CENTER, the point
at which the primary aircraft control would lock up. Some aircrafts mechanical primary control
installations will not allow this to occur and do not need the servo stops. This is a condition that
would result from the servo being back driven when the pilot operates the controls, or from the
servo itself driving the controls to a stop. To protect against this mechanical stops are supplied
with the servos. These stops are drilled so that they can be mounted at different angles as
required (18° intervals).

In addition to the proper use of the stop it is important to know the amount of travel on the
primary control that the servo can handle. With the push rod connected to the outermost hole (1
½”) the travel on the primary cannot exceed 2 ½”, the intermediate hole 2 1/16”, and the inner
hole 1 5/8”.

It is important to note that at the neutral point of the control the SERVO ARM must be
PERPENDICULAR to the push rod, and that the stop must be mounted so as to limit travel as
near as possible to equal amounts in both directions. In certain factory-designed installations
there may be well-proven exceptions.

There will be installations in which space does not permit the use of the stop. When this is done
the aircraft’s primary control stops must be positive and care must be taken to be sure that at the
neutral point the servo arm is perpendicular to the push rod, and that the travel limits of the servo
arm are not exceeded.

There are installations in which the travel of the push-pull tube exceeds the allowable 2 ½”. For
such installations, the drive can be applied to a bell crank at a radius point that moves the desired
2 ½” of maximum allowed travel in the outermost hole of the arm.

When there is no way to have a drive point of less than 2 ½” or when the primary control is cable­driven it is necessary to use the capstan-cable servo drive. When this is done the servo should be
mounted so that the 1/16” diameter cable which wraps around the capstan when extended parallel
to the primary cable is approximately 3/16” from the primary cable. If the primary control travel
does not exceed 5” the cable locking pin will be 180° away from the point at which the cable
leaves the capstan. When the primary control is at the neutral point this means the total cable
wrap around the capstan is 360°. If the primary control travel is greater than 5” the cable wrap is
720°and the pin is adjacent to the output point when the primary control is at the neutral point.

The cable clamps when properly installed will not slip and thus get loose, but it is desirable to
NICO press or swedge a fitting on to the cable so as to provide added assurance that the cable will

TruTrak Flight Systems Yaw Damper Installation Manual
December 2009 2 8300-063 Rev C